In recent years, there has been provided a 3GPP-standard CBS (Cell Broadcast Service) technique capable of simultaneously delivering messages from a delivery server on a carrier side to communication terminals existing in some specific area (e.g. see Patent Literature 1).
By means of this CBS technique, the service of simultaneously delivering, for example, “a forecast and a warning conforming to a general usage concerning an earthquake motion and a volcanic phenomenon caused by a generated fault motion” (so-called earthquake early warning, see Non Patent Literature 1) which has come to be delivered from the Japan Meteorological Agency due to revision of the Meteorological Service Act, emergency information provided by a municipality or the like, and some other information has been provided by a carrier to communication terminals existing in an area considered to be influenced by the information (e.g. see Non Patent Literature 2). Further, when a disaster or the like occurs, the carrier performs the service of setting up a disaster message board so as to allow communication with people in a disaster area since a vocal call becomes difficult to make due to network congestion (e.g. see Non Patent Literature 3).